Initial concentrations are the same at equilibrium?

[Tai Metzger 3K]

I was doing some practice problems and for a couple I found that x was found to be so small that the concentrations for the reactants were the same at equilibrium as they were initially. Is this possible and/or common? Thanks!

[KeyaV1C]

When K is really small, the value of x tends to be really small as well, barely changing the concentration of the reactants.

[Marni Kahn 1A]

This is seen quite often because we do a lot of examples with an infinitesimally small value of Ka

[Morgan Carrington 2H]

It is possible and commonly seen when doing acid and/or base equilibrium, but I would warn to be careful getting comfortable doing it because there are times when you can't use that rule.